Randomized clinical trial comparing the effects of post placement on failure rate of postendodontic restorations: preliminary results of a mean period of 32 months.

INTRODUCTION: The aim of this randomized clinical trial was to assess whether the placement of a fiber post (DT Light Post) (DT) and the amount of residual coronal dentin affect the time to failure of single-unit postendodontic restorations. METHODS: Ninety patients providing 120 teeth were selected. Three groups (n = 40) were defined on the basis of the amount of residual coronal dentin: 2-walls group, 2 or more coronal walls; 1-wall group, 1 coronal wall; no-wall group, no wall exceeding 2 mm above the gingival level. Within each group teeth were randomized and allocated to 2 intervention groups (n = 20), including subgroups no post (no root canal retention) and subgroups post (placement of DT). RESULTS: After a mean observation period of 32.4 (13.7) months in subgroups no post, the failure rates were 10%, whereas in subgroups post, failure rates of 7% were observed (P = .318). In no-wall group post placement significantly affected the time to failure of total restorations (P = .029, log-rank test). Teeth without post retention revealed a significantly higher failure rate (31%) compared with teeth restored with post retention (7%). CONCLUSIONS: Within the observation time of the present study, fiber post placement was efficacious to reduce failures of postendodontic restorations only with teeth that exhibited no coronal walls. Post insertion for teeth showing a minor substance loss should be critically reconsidered.

Influence of the canal contents on the electrical assisted determination of the length of root canals.

The purpose of this study was to compare the influence of the root canal status on the determination of the root canal length by an electronic apex locator in vital and necrotic canals and canals with root canal filling retrieval. One hundred seven teeth with a total of 171 canals with various contents (105 vital pulp, 47 necrotic pulp, and 19 retrieval of root canal filling materials) were measured for root canal length in vivo with the AFA Apex Finder. The distance between the file tip and the radiographic apex was also determined on radiographs. In 86% of the evaluated roots, the file tip position as indicated by the Apex Finder was located within 0.5 mm of a point 1.0-mm short of the radiographic apex. The Apex Finder showed higher accuracy for determining the apical constriction in vital canals (93.9%) than in necrotic canals (76.6%), and this difference was statistically significant (p < or = 0.05). The Apex Finder indicated the point -1 mm +/- 0.5 mm in canals with retrieval of root canal filling materials in 68.4% of these cases, but because of the small number of retrieval cases, this is not comparable statistically with vital and necrotic cases. The authors concluded that the AFA Apex Finder is highly accurate in vital canals.